Well, for a start, you get to be in the cool gang
But seriously, you are trading the easy maintenance of gas for diesel torque. That is mostly it.
I switched from gas to diesel a few months ago so here's a few points that comes to mind:
Maintenance is not that bad either. Oil and filter changes are more expensive but occurs far less often so its kinda a wash.
You must add fuel additives to every fill-up to protect the fuel pump.
Diesel needs a warm up as soon as its get a little chilly where gas is just start and go.
Turbo lag is a thing. Gas react like a sport car in comparison. On a diesel, when you want to pass, you need to be pre-emptive. Like you press the pedal, go to your notary, leave the boost on your will and maybe two generations after you die will get the boost you wanted.
Diesel engine sounds like a real truck. It's addictive.
Exhaust brake is probably my preferred thing I gained from gas. It's not a gimmick, it's worth it. I use it all the time.
And torque... Lots of torque... And again more torque.
So basically towing is just so much fun with a diesel.